The title is a tease. Sex and Broadcasting, Tim K. Smith’s long-overdue documentary on Wfmu -- America’s most celebrated freeform radio station -- isn’t at all sexy. (In fact, the film loudly flaunts the bodacious unsexiness of the Jersey City station’s variously overweight and grizzled DJs.) But Smith's film, which premiered at Doc NYC on Saturday and plays once more this Thursday night, is a funny, woozy, infectiously cheery look at a still-persevering (though struggling) national treasure.

Unsurprisingly, Wfmu’s shaggy-dog charm continues to be its saving grace. In the nearly 20 years since station manager Ken Freedman saved Wfmu from its bankrupt owner -- the now-defunct Upsala College -- countless record labels have either shut do...